Friday's horrific killings in a Connecticut elementary school focused renewed attention on mental illness in the U.S., ranging from discussions about the nature of the disease to how it should be treated.

Little is known about the shooter, 20-year-old Adam Lanza, beyond accounts that he was highly intelligent and was home-schooled by his mother after years of struggling in various public schools. Reports that he had Asperger’s Syndrome, which is part of the autism spectrum disorder, are unconfirmed but have widely circulated.

Advocates for people with autism were quick to note that there is no connection between violent behavior and the disorder, which is generally characterized by social awkwardness, an inability to read other people’s social cues, and exceptional talents in certain areas.

“There is absolutely no evidence or any reliable research that suggests a linkage between autism and planned violence,” the national Autism Society said in a statement. “To imply or suggest that some linkage exists is wrong and is harmful to more than 1.5 million law-abiding, nonviolent and wonderful individuals who live with autism each day.”

Nick Piazza, a University of Toledo professor who is a psychologist and a licensed professional clinical counselor, echoed that statement.

“[Asperger’s is] really an impairment in your ability to relate to people interpersonally,” he said. “In some severe cases you may see anger management issues, but you wouldn’t see that associated with violence any more than just by chance.”

Scott Badesch, president of the national Autism Society, said his organization has been deluged with calls since the story was first reported Friday.

“What we have been saying is that there is no known link between autism and planned violence, and we’re using the word 'planned' because every one of us may engage in violent outbursts,” he said.

Lanza’s case also has raised the issue of what should be done for people like him if loved ones or friends know the person has a mental illness and could be prone to violence. In the 1950s and 1960s community mental health hospitals were prevalent until concerns about the way patients were handled led to a nationwide movement to shift treatment to outpatient settings.

“The idea behind deinstitutionalization was to take all these individuals out of the very restrictive hospitals, which was to a lot of people like imprisoning these people,” Mr. Piazza said.

The goal was for people to be treated by community mental health agencies, psychologists, and other healthcare professionals in outpatient settings.

“A lot of people were turned out, but the services were never fully implemented to handle them,” Mr. Piazza said.

Jean Drees, director of marketing for Harbor, a Toledo mental health provider, said deinstitutionalization led to funding problems and inconsistent mental health care from state to state.

“Part of the bad news is that this sheds light on the breakdown of the system,” she said, noting that political leaders already are talking about ways to address the concerns.

Mr. Piazza, who has worked in mental health-related fields since 1975, said many mental illnesses can be managed through therapy and drugs much more effectively than they could 30 or 40 years ago, which has decreased the need for inpatient hospitals.

But those treatments are expensive and often not covered by insurance, he said, leaving patients and their families to try and manage issues such as schizophrenia or bipolar disorder.

“Most people just in their day-to-day lives are not equipped to deal with something like this on their own,” he said. “The big problem is that these are very expensive services. Insurance agencies don’t like to cover these issues.”

He said he became frustrated this weekend listening to people pointing to the shootings as evidence that the nation’s mental health treatment system is broken.

“The mental health system is doing everything it can to help people with what it has,” he said. “You can’t turn all these people out of the hospitals and say we’re going to treat them with local services and then not support the local services.”

He also cautioned against jumping to conclusions about Lanza and his motives until a full investigation is conducted.

“In looking at this, the important thing to keep in mind is that this is a very complicated and complex event, a tragedy. It’s horrific but the thing we need to keep in mind is that complex situations don’t lend themselves to simple solutions very well.

“We need to be careful that we don’t stigmatize people and that we don’t go off with a half-baked notion of what we think occurred here.”

Mr. Badesch said the Autism Society received numerous calls from people who have autism and Asperger’s concerned that others will jump to erroneous conclusions about them.

“This is another obstacle put in the way of [their] success. I had a guy call me today and say that he’s afraid that his boss will think he’s a shooter that’s going to shoot up the office.”